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The effects of hypobaric hypoxia on aspects of oxygen transport and utilization in mice with an inherited tolerance for hypoxic exercise

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Melissa H. Ernst (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Stephen Kinsey

Abstract: The effects of chronic hypoxia on properties of oxygen supply and demand were investigated in mice found to have inherited differences in hypoxic exercise tolerance (43). Previous results demonstrated that two major loci and an unknown number of modifying genes were associated with the differences in hypoxic exercise performance following 8 weeks exposure to hypobaric hypoxia in two inbred strains of mice, BALB/cByJ (C) and C57BL/6J (B6), and their F1 hybrid (43). The three strains had similar capacities for hypoxic exercise following exposure to normoxia. After 8 weeks of hypoxic exposure, C mice showed little improvement in hypoxic exercise performance while B6 mice had a significant improvement in fatigue resistance compared to normoxic mice. Acclimated F1 mice, however, had a hypoxic exercise tolerance that far exceeded that of either of the two parental strains. In the present study, all of the mouse strains responded to hypoxia by elevating the hematocrit, hemoglobin, and BPG concentrations; although, hypoxia-intolerant C mice had lower hematocrit and hemoglobin concentrations following acclimation than both B6 and F1 mice. Mitochondrial densities and distributions, as well as COX activities did not differ among strains or treatments, suggesting that the muscles within the three strains have comparable oxygen demands. F1 mice did, however, have very low concentrations of BPG relative to the other two strains, and reduced concentrations of myoglobin in both skeletal and cardiac muscle following hypoxic exposure. This suggests that the superior exercise performance of the F1 mice may result from a relatively higher rate of oxygen supply to the muscles, such that high concentrations of BPG and myoglobin are not required to keep up with oxygen demand.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Keywords
Anoxemia, Mice as laboratory animals, Oxygen--Physiological effect, Oxygen transport (Physiology)
Subjects
Oxygen transport (Physiology)
Mice as laboratory animals
Oxygen -- Physiological effect
Anoxemia